Such generic slide valves are used for, among other things, opening and closing lines for the conveyance of media, such as for example in purification plants with raw sewage or sludge, in chemistry involving granulated material, chemical liquids etc., in the food industry involving drinking liquids, cereals or rinsing fluids or similar.
With one such slide valve according to publication EP-A-2 216 572, a two-part housing and a slide plate that can be moved relative to the latter in order to open or close a through-opening is provided. With this slide valve, longitudinal seals are contained in the housing above the through-opening, which longitudinal seals are aligned transversely to the direction of shifting the slide plate and form a flexible seal between the housing and the slide plate on the upper side.
In addition, for the lateral and lower sealing between the slide plate and the housing, a sealing cord or the like and an end seal are provided which together form an all-round seal between the slide plate and the housing in the closed state. A permanent and secure seal is thus formed when the slide valve is closed. However, when there is a high degree of media pressure leaks may occur between the individual seals.
However, such slide valves are also used in lines for the conveyance of media with abrasive properties, such as oil sand, wherein the lines have flow-through openings with dimensions of up to 1,000 mm and are operated at high pressures. For example, when oil sand is to be conveyed, the latter contains mixtures of minerals which are the size of grains of sand, the size of a fist or clump-sized. Since these lines are generally laid outdoors, they are also subjected to large temperature differences. Additional demands are therefore made of the slide valve so that it always performs the required sealing function and thereby has a long service life.